Stem Cell Research
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Committee on Jewish Law and Standards of the Rabbinical Assembly YD 336.2002 Stem Cell Research RABBI ELLIOT N. DORFF This paper was approved by the CJLS on March 13, 2002. The answer to question 1 received a vote of fifteen in favor and one abstention (15-0-1). Voting in favor: Rabbis Kassel Abelson, Ben Zion Bergman, Elliot N. Dorff, Paul Drazen, Robert Fine, Baruch Frydman-Kohl, Susan Grossman, Alan B. Lucas, Daniel Nevins, Paul Plotkin, Joseph Prouser, Mayer Rabinowitz, Avram Israel Reisner, Joel Rembaum, and Gordon Tucker. Abstaining: Rabbi Joel Roth. The answer to question 2 received a vote of fourteen in favor, one against, and one abstention (14-1-1). Voting in favor: Rabbis Kassel Abelson, Ben Zion Bergman, Elliot N. Dorff, Paul Drazen, Robert Fine, Baruch Frydman-Kohl, Alan B. Lucas, Daniel Nevins, Paul Plotkin, Joseph Prouser, Mayer Rabinowitz, Avram Israel Reisner, Joel Rembaum, and Gordon Tucker. Voting against: Rabbi Susan Grossman. Abstaining: Rabbi Joel Roth. YNWD 1. May embryonic stem cells from frozen embryos originally created for purposes of procreation or embryonic germ cells from aborted fetuses be used for research? 2. May embryonic stem cells from embryos created specifically for research, either by combining donated sperm and eggs in a petri dish or by cloning be used for research? YXD The Current State of the Science of Stem Cells Definitions and Properties What are stem cells, and why are we interested in doing research on them? The following paragraphs that answer those questions are quoted from a document issued in May, 2000 by the Director of the National Institutes of Health entitled “Stem Cells: A Primer”:1 Stem cells are best described in the context of normal human development. Human development begins when a sperm fertilizes an egg and creates a single cell that has the potential to form an entire organism. This fertilized egg is totipotent, meaning that its potential is total. In the first hours after fertilization, this cell divides into identical toti- potent cells. This means that either one of these cells, if placed into a woman’s uterus, has the potential to develop into a fetus. In fact, identical twins develop when two totipotent cells separate and develop into two individual, genetically identical human beings. Approximately four days after fertilization and after several cycles of cell divi- sion [up to the 32-cell stage], these totipotent cells begin to specialize, forming a _________________________________________________________________________________ The Committee on Jewish Law and Standards of the Rabbinical Assembly provides guidance in matters of halakhah for the Conservative movement. The individual rabbi, however, is the authority for the interpretation and application of all matters of halakhah. hollow sphere of cells, called a blastocyst. The blastocyst has an outer layer of cells, and inside the hollow sphere there is a cluster of cells called the inner cell mass. The outer layer of cells [the “trophectoderm”] will go on to form the placenta and other supporting tissues needed for fetal development in the uterus. The inner cell mass cells will go on to form virtually all of the tissues of the human body [in a process that begins with “gastrulation” during the period between 16 and 22 days of gestation] . Although the inner cell mass cells can form virtually every type of cell found in the human body, they cannot form an organism because they are unable to give rise to the placenta and supporting tissues necessary for development in the human uterus. These inner mass cells are pluripotent – they can give rise to many types of cells but not all types of cells necessary for fetal development. Because their potential is not total, they are not totipotent and they are not embryos. In fact, if an inner cell mass cell were placed into a woman’s uterus, it would not develop into a fetus. The pluripotent stem cells undergo further specialization into stem cells that are committed to give rise to cells that have a particular function. Examples of this include blood stem cells which give rise to red blood cells, white blood cells and platelets; and skin stem cells that give rise to the various types of skin cells. [Muscle, cartilage, bone, liver, brain, and fat are other examples of adult stem cells.] These more specialized stem cells are called multipotent. Two things should be noted. First, the word “adult” as used in the phrase “adult stem cells” refers to any person after birth. Thus adult stem cells from infants can and have been used to cure leukemia in siblings, for example. Some very recent research suggests that some adult stem cells may be pluripotent. Nothing in this responsum should suggest that research on adult stem cells should be abandoned; on the contrary, every effort should be expended to use adult stem cells for as many cures as possible. It should not, however, lead us to abandon embryonic stem cell research, for that still holds out more hope to accomplish all the uses de- scribed in the next section. Second, in normal human development, embyronic stem cells create the various organs and tissues of the body and then turn off; otherwise, we would have multiple heads, legs, hearts, etc., and it is questionable whether the uterus would be able to hold a human being or give birth to one. Unlike human fetal development, scientists are interested in removing embryonic stem cells to create stem cell lines, which would theoretically multiply stem cells indefinitely — although stem cells naturally “senesce” after dividing up to 100 times. Scien- tists then want to learn how to transform stem cells into needed tissues or organs and how to stop them when they reach the desired state. In addition to embryonic stem cells, scientists are interested in embryonic germ (EG) cells. Those are cells from the gonadal ridge in the early embryo that in the process of the fetus’ development are set aside and protected from maturing. They migrate through the fetus to the ovary or testes, where they form the egg and sperm cells. If removed from the fetus and grown in culture, they behave much like embryonic stem cells. Potential Uses of Stem Cells Adult stem cells, which are normally used by the body for maintenance, have already proven useful in drug development, in treatment of diseases like osteoporosis and leukemia, and in cardiac and cartilage care. Research into further potential uses of adult stem cells in blood, skin, and other parts of the body should certainly go forward. Scientists, though, are especially interested in doing research on the cells normally used by the body for development, i.e., our embryonic stem cells (ES) and our embryonic germ cells (EG). While some adult stem cells may be pluripotent, most have been differentiated to the point that they can only produce other cells like themselves (they are only “multipotent”), with minimal ability to transform into other kinds of cells. In contrast, embryonic stem cells can and do convert into all of the tissues of the body (they are “pluripotent”). Because ES cells have this greater ability to mutate, scientists engaged in research on them hope, according to the N.I.H. document quoted above, to learn or do at least the following three things: A. Learn About the Process of Cell Specialization How do stem cells decide which tissues to become and how many to make of each type of tissue? We know that turning genes on and off is central to the process of human development, but we do not know much about how these decisions are made in the process of human development or how stem cells are turned on or off. Some of our most serious medical conditions, such as cancer and birth defects, are due to abnormal cell specialization and cell division. A better understanding of normal cell development is necessary for scientists to learn what goes wrong with cells when cancer or birth defects occur so that hopefully some day such abnormal developments can be arrested and reversed. Because of their level of differentiation, adult stem cells seem to be a much less likely source for gaining this knowledge than embryonic stem cells promise to be. Thus even if adult stem cells can ultimately be used for the other two purposes listed below, embryonic stem cell research will be necessary to accomplish this end. Furthermore, even with some preliminary results indicating that some adult stem cells may be pluripotent, embryonic stem cell research still holds out greater hope for these other two purposes as well. B. Test Drugs More Safely and Efficiently Research on pluripotent human stem cells could also dramatically change the way we develop drugs and test them for safety. New medications could be initially tested using human cell lines before testing them on human beings. I am currently serving on the National Human Resources Advisory Commission of the Department of Health and Human Services, whose mandate is to review and revise the federal guidelines for research on human subjects. Widely publicized fatal experiments that killed Jesse Gelsinger at the University of Pennsylva- nia and Ellen Roche at the Johns Hopkins Medical Center have brought to light other questionable practices used by pharmaceutical companies and academic medical centers in testing drugs. The pressures to gain reputation and money in this field are enormous, and so strict requirements to protect human subjects are necessary. On the other hand, we all have benefitted immensely from the breakthroughs in drugs during the last six decades, beginning with penicillin in 1938, and that can only happen if drugs are ultimately tested for their safety and effectiveness on human beings.